Hydraulic lifter with lash compensator



United States Patent l1n3,542,001

[72] Inventor Gerald D. Line 2,874,684 2/1959 Thompson 123/90 S iMichigan 3,1 24,1 15 3/1964 Vo'orhies 123/90 [211 App]. No. 770,4823,142,290 7/1964 Lesher..;. 123/90 [22] Filed Oct. 25, 1968 3,304,9252/1967 Rhoads 123/90 [45 Patented 1970 Primary ExaminerAl Lawrence Smith[73 Assgnee gfgz zz fg r Anorney Yount, Flynn 8; Tarolli a corporationof Ohio [54] HYDRAULIC LIFTER WITH LASH ABSTRACT: An improved hydrauliclifter or lash ad uster has COMPENSATOR l7 Claims8Dmwing Figs. acompensator assembly for providing a predetermmed amount of lash in avalve train. The compensator assembly in- U-S- N clude's a member whichis biased outwardly a Spllllg (0 pro.

l23/9055 vide a clearance, corresponding to the predetermined lash, [51]Int. Cl... F01ll/l8, between th compensator membe and a stop surface ona 1/24 plunger. The compensator member is brought into engage- [50]Field of Search 123/90al1 mem with the Stop surface by operation f a camiated References Cited with the valve train to thereby eliminate theclearance and take up the lash. A stop means is provided to limitoutward UNITED STATES PATENTS movement ofthe compensator member underthe influence of 2,812,750 11/1957 Lesher 123/90 the spring.

Paten ted Nov. 24, 1910 3,542,001

Sheet 1 M2 FIG.2-

FIG .4

' INVENTOR. GHQ/1L0 Q L/IVE Patented Nov. 24, 1970 3,542,001 I 90b FIG 8FIG. 6

INVENTOR. GERALD 0. LINE BY ,y AZOR/VEYS HYDRAULIC LIFTER WITH LASI-ICOMPENSATOR This invention relates to a hydraulic lifter or lashadjuster having a compensator assembly for providing a predeterminedamount of lash in a valve train.

During operation of an engine, a hydraulic lifter often tends to obtaintoo large an axial extent due to pumping up" of the lifter. This pumpingup" of the hydraulic lifter results from the lifter responding totemporary or momentary slack in the valvetrain which may be caused byresilient deflection and separation of various parts of the valve trainand the action of the valve spring. Upon a pumping up of the hydrauliclifter, the associated valve cannot close and the efficiency ofoperation of the engine is decreased=ln addition, the valve may be heldopen due to eccentricity of the cam base circle or deflection of thecamshaft.

Accordingly, it is an object of this invention to provide a new andimproved hydraulic lifter having a compensator assembly for establishingvalve train lash to take up temporary shock in a valve train to therebyprevent pumping up of the lifter.

Another object of this invention is to provide a new and improvedhydraulic lifter having a compensator assembly which provides aclearance between a stop surface on a plunger member and a compensatormember to thereby provide a corresponding lash in the valve train.

Another object of this invention is to provide a new and improvedhydraulic lifter having a compensator assembly including a spring biasedcompensator member for providing lash in a valve train by establishing aclearance between the compensator member and a stop surface on a plungermember, the

compensator member being moved into engagement with the stop surface inresponse to operation of a cam to eliminate the clearance and take upthe lash in the valve train.

These and other objects and features of the invention will become moreapparent upon a consideration of the following description taken inconnection with the accompanying drawings wherein: FIG. 1 is anillustration of a hydraulic lifter or lash adjuster, constructed inaccordance with the present invention, in a valve train for operating avalve of an overhead cam engine;

FIG. 2 is a sectional view, taken along line 2-2 of FIG. 1, illustratingthe internal structure of the hydraulic lifter;

FIG. 3 is an enlarged sectional view illustrating the structure of acompensator assembly which is included in the hydraulic lifter of FIG. 2and provides a predetermined clearance and corresponding lash in thevalve train of FIG. 1;

FIG. 4 is an enlarged sectional view, similar to FIG. 3, illustratingthe compensator assembly in an operated position in which the clearanceis eliminated to take up the corresponding lash in the valve train;

' cordance with the present invention and adapted to be used in anengine having a camshaft mounted in the engine block.

The present invention provides a hydraulic lifter or lash adjusterhaving an improved compensator assembly in association with a pair ofplunger members for preventing pumping up or undesirable lengthening ofthe lifter by providing for the establishing of a predetermined amountof lash in a valve train. In addition, the compensator assembly alsoprevents an associated valve from being held open due to eccentricity ofthe cam base circle or deflection of the camshaft by taking up orabsorbing the dimensional increase or negative clearance in the valvetrain caused by the eccentricity of the cam or deflection of thecamshaft. The compensator assembly includes a spring which pressesa-compensator member toward one of This lash is taken up by eliminationof the clearance as a result of movement of the compensator member intoengagement with the stop surface upon operation of a cam associated withthe valve train. The compensator assembly prevents pumping up of thehydraulic lifter by reestablishing the clearance. Reestablishing of theclearance prevents "pumping up" of the lifter by absorbing any temporaryor momentary slack in the valve train due to the action of a spring forclosing the valve, deflection of parts of the valve train, and/orinstantaneous separation of the parts of the valve train. Thecompensator absorbs a dimensional increase or negative clearance in thevalve train by enabling the compensator member and one plunger member tomove toward the other plunger member. I Although a hydraulic lifter orlash adjuster l0 constructe in accordance with the present invention canbe used in many different types oflengines, the hydraulic lifter isillustrated in FIG. 1 in a valve train 12 of an engine 14 having an overhead cam 16. The valve train 12 is actuated by the cam l6 to operate avalve 20 (shown in FIG. 1 in a closed position) to control the flow ofgases from a combustion chamber 22 in a known manner. To operate thevalve 20, the valve train 12 includes a rocker arm 26' which has an endor nose portion 28 for engaging the stem30 of the valve. The oppositeend 31' of the rocker arm 26 is connected by a clip 32 to the hydrauliclifter l0. 7

Upon rotation of the cam 16ina clockwise direction, a leading ramp 36 ofan actuating or nose portion 38 of the cam engages a follower surface 40on the rocker arm 26 to open the valve 20 by pivoting the rocker armabout the hydraulic lifter l0. Continued rotation of the cam 16 bringsthe trailing ramp 42 of the cam into engagement with the followersurface 40. The valve 20 then moves toward the illustrated closedposition under the influence of valve spring 44. After a base circleportion 48 of the cam 16 engages the follower surface. 40, the valve 20is held closed by the valve spring 44 until the leading ramp 36 of thecam is again brought into engagement with the follower surface 40.

The hydraulic lifter l0 adjusts the valve train 12 to maintain apredetermined relationship between the rocker arm 26 and cam 16 eventhough the dimensions ofthe valve 20 and rocker arm 26 may vary due towear, thermal effects and other reasons. To this end, the hydrauliclifter 10 includes a generally cylindrical, stationary outer housing orcasing 52 having a central chamber or cavity 54 (See FIG. 2) in which afirst or inner plunger member 56 and a second or outer plunger 58 areslidably mounted in a coaxial relationship. The plunger members 56 and58 define central cavities 62 and 64 which cooperate to form a fluidreservoir 66 for holding oil or other lubricant. The reservoir 66isconnected in fluid communication with an oil pump or other source oflubricant under pressure (not shown) by holes or apertures 70 and 72 inthe body and plunger member 52 and 58 and by passages 74 in the engineblock.

A check valve assembly 78 cooperates with the plunger members 56 and 58to. compensate for dimensional changes in the valve train 12 by varyingthe axial extent of the hydraulic lifter 10 to thereby maintain apredetermined relationship between the cam 16, rocker arm 26 and valve20 (See FIG. 1). This is accomplished by providing a pressure chamber 80in which fluid is subjected to pressure by the downward force of therocker arm 26 on the plunger members 56 and 58 when? the operatingportion or nose 38 of the cam 16 engages the follower surface 40 to openthe valve 20 (FIG. 1). Some of the fluid in the pressure chamber 80(FIG, 2) is forced out of the chamber along a relatively small clearance82 between the cylindrical peripheral surfaces of the plunger members 56and 58 and the cylindrical inner surface of the body 52. This leakage offluid is commonly referred to as leakdown and results in a slight inwardmovement of the plunger members 56 and 58 and a correspondingcontraction of the pressure chamber 80.

When the force against the outer plunger 58 is reduced by engagement ofthe base circle 48 of the cam 16 with the follower surface 40 of the.rocker arm 26, a plunger spring 84 in the pressure chamber 80 pressesthe plungers 56 and 58 outwardly to press the rocker arm 26 against thebase circle 48 of the cam 16. This outward movement of the plungermembers 56 and 58 causes the pressure chamber 80 to expand slightly andreduces the fluid pressure within the chamber. Fluid pressure in thereservoir 66 is then greater than the fluid pressure in the chamber 80and a valve member 86 of the check valve assembly 78 (FIG. 2) is movedout of engagement with a valve seat 88 against the influence of a valvespring. 90 to enable fluid to flow from the reservoir 66 through apassage 94 to the pressure chamber 80 to replace the fluid whichpreviously leaked out of the pressure chamber. If the effective lengthof the valve train 12 should increase from one revolution of the cam 16to the next, the distance which the plunger spring 84 moves the plungersS6 and 58 and the amount of replacement fluid which flows into thepressure chamber 80 is decreased to thereby decrease the effective axialextent of the hydraulic lifter 10. Conversely, if the effective lengthof the valve train 12 should decrease from one revolution of thecamshaft 16 to the next, the plunger spring 84 moves the plunger members56 and 58 outwardly to expand the pressure chamber 80 and enable arelatively large amount of replacement fluid to flow into the pressurechamber to thereby effect an increase in the axial length of thehydraulic lifter 10. In this manner the check valve assembly 78 andplunger members 56 and 58 cooperate to maintain a predeterminedrelationship between the cam'16, rocker arm 26 and valve 20 even thoughthe effective dimensions of the valve train 12 change during operationof the engine 14. Of course, a ball-type check valve member could beused instead of the member 86.

If temporary or momentary slack should occur in the valve train 12 dueto the action of the valve spring 44, deflection of the parts of thevalve train, or instantaneous separation of the parts of the valvetrain, the check valve assembly 78 responds to this temporary ormomentary slack to increase the size of the pressure chamber 80 and theeffective axial length of the hydraulic lifter 10 more than is necessaryto maintain the desired predetermined relationship between the cam 16,rocker arm 26 and valve 20. This undesired increase in the effectiveaxial length or extent of the hydraulic lifter 10 due to temporary ormomentary slack in the valve train 12 is commonly called pumping up ofthe hydraulic lifter l and results in the valve 20 being held in an opencondition due to a raising or outward movement of the plunger member 58and a corresponding lowering or inward movement of the nose portion 28of the rocker arm 26. Of course, when the valve member 20 is held in apartially opened condition due to a pumping up of the hydraulic lifter10, the flow of gases from the combustion chamber 22 is improperlycontrolled and there is a decrease in operating efficiency of the engine14. In addition to being susceptible to being held open due to a pumpingup of the hydraulic lifter 10, the valve 20 will be held open due toeccentricity of the cam 16 or deflection of the camshaft.

In accordance with the present invention, a compensator assembly 100 isprovided in association with the plunger memlifter and for taking up orabsorbing negative clearance in the valve train. The compensatorassembly 100 prevents pumping up of the hydraulic lifter 10 by providinga clearance or space 104 (FIGS. 2 and 3) which is taken up-or absorbedupon downward or inward movement of the rocker arm 26 under theinfluence of the cam 16. Upon the subsequent occurrence of temporary ormomentary slack in the valve train, the clearance 104 is at leastpartially reestablished to prevent the check valve assembly 78 fromresponding to the momentary slack and pumping up the lifter 10. Theclearance 104 is formed between an annular stop surface 108 bers 56 and58 for preventing pumping up of the hydraulic on an outer end portion ofthe inner plunger member 56 and a parallel annular stop surface 110 onan annular head portion 114 of a compensator member 116. When theactuating portion 38 of the cam 16 moves the rocker arm 26 downwardly(See FIG. 1), an annular end surface 118 of the outer-plunger member 58is pressed downwardly against an annular outer surface 122 of the headportion 114 (FIG. 3) to force the compensator member 116 axiallyinwardly or downwardly against the influence of a compensator spring 120which is located between a base portion 123 of the compensator member116 and an end wall 124 of the inner plunger member 56 (FIG. 2). Thestop surface 110 on the head portion 114 of the compensator member 116is then pressed against the stop surface 108 on the inner plunger member56, in the manner illustrated in FIG. 4, to enable force to betransmitted from the outer plunger member 58 through the compensatormember 116 to the inner plunger member 56 to apply pressure to the fluidin the pressure chamber (FIG. 2).

Pumping up of a hydraulic lifter may result from the occurrence oftemporary or momentary slack in the valve train 12 when the crest ornose of the actuating portion 38 of the cam 16 (FIG. 1) is moving ontoor off of the follower surface 40. During this period of operation, thecompensator assembly expands axially from the operated condition, shownin FIG. 4, to the normal or expanded condition, shown in FIG. 3. Anytemporary or momentary slack in the valve train is absorbed or taken upby a reestablishment of the clearance 104 under the influence of thecompensator spring 120. Accordingly, the compensator spring moves thecompensator member axially outwardly from the position shown in FIG. 4toward the position show in FIG. 3 to maintain the plunger member 58 inengagement with the rocker arm 26 and absorb momentary slack caused by atemporary decrease in the effective length in the valve train 12. Whenthe effective length of the valve train is increased, that is when themomentary slack is removed from the valve train, the actuator member 116is moved inwardly toward stop surface 108. The compensator spring exertsa force, tending to separate the plunger members 56 and 58, which isgreater than the force exerted by the plunger spring 84. In theillustrated embodiment, the compensator spring 120 has a higher spring,rate than does the plunger spring 84.

From the foregoing description it can be seen that the compensatorassembly 100 prevents a pumping up" of the hydraulic lifter 10 byabsorbing temporary or momentary slack in the valve train 12 by movingthe compensator member 116 under the influence of the compensator spring120. Movement of the compensator member 110 temporarily reestablishesthe clearance 104 to enable the outer plunger member 58 to moveoutwardly without a corresponding outward movement of the innerplungermember 56 under the influence of the plunger spring 84. Thisoperation of the compensator assembly 100 prevents unwanted operation ofthe valve assembly 78, in response to movement of the inner plungermember 56, by absorbing the temporary slack and effectively insulatingthe inner plunger member and the valve assembly from the effects of theoccurrence of the temporary slack.

The compensator assembly 100 is effective to absorb or take up negativeclearance in the valve train resulting from eccentricity of the cam 16or deflection of the associated camshaft. This negative clearance istaken up by inward movement of the outer plunger member 58 andcompensator member against the influence of the compensator spring 120.This inward movement decreases the extent of the clearance 104 andenables the valve 20 to close.

A stop ring or member is provided for limiting outward rocker arm 26,the compensator assembly 100 moves from the operated condition of FIG 4to the normal condition of FIG. 3. As this is occurring the spring 120moves the base portion 122 of the compensator member 116 through adistance 138 (FIG. 4) which is equal to the clearance 104 to bring anouter or upper limit or stop surface 140 of the compensator member 116into engagement with the stop ring 130 (FIG. 3) to thereby reestablishthe clearance 104. Continued movement of the trailing ramp 42 relativeto the follower surface 40 then enables the plunger members 56 and 58 tobe moved axially outwardly by the plunger spring 84 to thereby expandthe pressure chamber 80 .(See FIG. 2) and open the valve as sembly 78 toenable replacement fluid to flow through the passage 94 into thepressure chamber in the manner previously explained. It should be notedthat the valve spring44 (See FIG. I) has a higher load or spring ratethan both the compensator spring 120 and plunger spring 84 so that thevalve 20 is not forced open by the combined action of these two springs.

For purposes of affording a more complete understanding of theinvention, several modified forms of the invention are shown in FIGS.5-8. In these modified forms or embodiments of the invention numeralslike those used in connection with the embodiment of FIGS. 1-4. havebeen used to designate like parts with the suffix letters a, b and beingemployed to distinguish the elements associated with FIGS. 5, 6 and 7,and 8, respectively. It should be understood that the invention is notto be limited to the particular embodiments described herein since manyother embodiments come within the true spirit and scope of theinvention.

The hydraulic lifter 10a of FIG. includes a body or casing 52am which afirst or inner plunger member 560 and a second or outer plunger member580 are slidably positioned. A check valve assembly (not shown), similarto the check valve assembly 78 of FIG. 2, is associated with the innerplunger member 56a to control the flow of fluid or lubricant from areservoir 66a to a pressure chamber (not shown). A compensator assembly100a is provided in association with the plunger members 56a and 58a toprevent a pumping up" of the hydraulic lifter a by resiliently absorbingor taking up temporarv slack in a valve train in much the same manner asin which the compensator assembly 100 of FIGS. 24 prevents the hydraulicvalve lifter 10 from being pumped up The compensator assembly 100aincludes a compensator member 1160 having a flat, annular disklikeconfiguration similar to that of a washer. The compensator member 1160is normally pressed against a stop ring or member 1300 by a compensatorspring 120a to provide a clearance 104a between an annular stop surface1080 on the inner plunger member 56a and a parallel annular stop surface110a formed on an inner side of the compensator member 116a.

Operation of a cam. similar to the cam '16 of FIG. 1, results in theplunger member 58a of the hydraulic lifter 100 being pressed inwardlyagainst the influence of the compensator spring 120a to take up oreliminate the clearance 104a bypressing the surface 1100 of thecompensator member 116a into abutting engagement with the stop surface108a on the inner plunger member 56a. If temporary or momentary slackshould occur in the valve train upon further rotation of the cam. thistemporary or momentary slack is absorbed or taken up by reestablishingthe clearance 104a in the manner previously explained in connection withthe embodiment of FIGS. 24 to thereby prevent a pumping up of thehydraulic lifter 1011. It should be noted that the compensator member116a is chamber 80b in association with the inner plunger member 56b tocontrol a flow fluid or lubricant from a reservoir 66b through a passage94b into the pressure chamber 80b and thereby adjusts the extent of thehydraulic lifter 10b in the manner previously explained in connectionwith the hydraulic valve lifter 10 of FIGS. 24. A compensator assembly10% is provided in association with the plunger members 56b and 58b toprevent pumping up of the hydraulic lifter 10b by resiliently absorbingor taking up temporary slack in an associated valve train resulting froma deflection or separation of parts of the valve train and/or the actionof a valve spring (similar to the valve spring 44 of FIG. 1). To thisend the compensator assembly 10% includes a compensator member 116bhaving a cylindrical pin like configuration with opposite end portions150 and 152 located in openings or apertures 154 and 156 in the innerplunger member 56b. The compensator member or pin ll6b has a diameterwhich is smaller than the a diameter of the circulator openings 154 and156 to provide a clearance 104b between a stop surface portion 108b ofthe openings 154 and 156 and lower or inner stop surface portions ll0bof the ends l50.and 152 of the compensator member 116b.

Upon rotation of the cam (not shown), the hydraulic lifter 10b isactuated to move the compensator member l16b inwardly or downwardlyagainst the influence of a compensator spring 120b This movement takesup or eliminates the clearance l04b by moving an outer or upper stopsurface portion 162 of the compensator member l16b away from outer orupper stop surface positions 166 (FIG. 7) of the openings 154 and 156and through a distance corresponding to the clearance 104b. It should benoted that the stop surface portions 166 function in the same manner asdo the stop rings 130.

and 130a of the embodiments of FIGS. 25 to limit the outward motion ofthe compensator member 1l6b under the influence of the spring 12%.

The compensator assembly 100b resiliently absorbs or takes up temporaryor momentary slack in the valve train to prevent a pumping up" of thehydraulic valve lifter 10b in the manner previously explained inconnection with the valve lifter 10 of FIGS. 24. Thus, once thecompensator assembly l00b has been actuated to the operated condition ofFIG. 7, the com-' pensator spring 120b moves the compensator member 1l6baway from the stop surface l08b to at least partially reestablish theclearance l04b and thereby absorb or take up any temporary or momentaryslack in the valve train. While the compensatormember l16b has beenillustrated in FIGS. 6 and 7 as having a generally pin likeconfiguration, it is contemplated that compensator members havingdifferent configurations could be loosely mounted in openings ofaconfiguration other than that of the openings 154 and 156 to provide asuitable clearance between an inner or lower portion of the compensatormember and a stop surface.

Although the hydraulic lifter 10 has been previously depicted herein inassociation with a valve train 12 (-See FIG. 1) of an over head camengine 14, it is contemplated that hydraulic lifters constructed inaccordance with the present invention and having compensator assembliessimilar to the compensator assemblies 100, 100a and 10% will be used inassociation with other known types of engines wherein the cam shaft ismounted in the block of the engine and the valve train includes a rockerarm which is operated in a known manner by a push rod. This adaptationof the hydraulic lifter is clearly illustrated inthe embodiment of FIG.8 wherein the hydraulic lifter 100 is shown in association with a cam16c and a push rod 200.

The hydraulic lifter 10c includes a casing or body 520 in which a firstor inner plunger member 560 and a second or outer plunger member 580 areslidably mounted. A check yalve assembly, similar to the check valveassembly 78 of FIG. 2, is associated with the inner plunger member 56cfor controlling the flow of fluid or lubricant from a reservoir 66c to apressure chamber, similar to the pressure chamber of FIG. 2. Acompensator assembly 1000 is combined with the outer plunger member 580and functions in a manner similar to the compensator member 116 of FIG.2 to establish a clearance 1040 between an annular stop surface 1080 anda stop surface 1100 formed on an inner or lower portion of the plungermember 58c. The plunger member 580 is pressed outwardly or upwardly by acombined plunger and compensator spring 204 which is positioned in afluid or lubricant reservoir 66c formed in the inner plunger member 56c.A stop ring or member 130s is mounted in a groove 1320 formed in theinner plunger member 560 to engage an outer stop surface 1220 on theplunger member 580 to limit outward movement of the plunger member 580under the influence of the spring 204.

Upon operation of the cam 160, the body 52c and push rod 200 are raisedto open a valve, similar to the valve 20. Upon this movement of the body52c, the spring 204 is compressed by relative movement between the innerand outer plunger members 560 and 580 so that the plunger member 580 isbrought into engagement with the stop surface l08c. The compensatorassembly 1000 prevents pumping up of the hydraulic lifter 100 byresiliently absorbing or taking up temporary or momentary slack in thevalve train, the spring 204 presses the plunger member 580 outwardly toat least partially reestablish the clearance 104C. Since the temporaryslack is taken up by the operation of the compensator assembly 1000. Acheck valve assembly, similar to the check valve assembly 78, associatedwith the inner plunger member 56c is not operated in response to theoccurrence of the temporary slack to provide a pumping up" or undesiredextension of the effective length of the hydraulic lifter 10c.

In view of the foregoing description, it is apparent that each of thehydraulic lifters 10. 10a, 10b and 10c have a compensator assembly 100,100a, 1001: or lc for providing for the establishing of a predeterminedclearance and a corresponding lash in a valve train to thereby preventpumping up of the hydraulic lifter and for taking up negative clearancein the valve train This predetermined clearance is established between astop surface formed on the inner plunger member and a similar stopsurface on a compensator member. Upon operation of a cam associated withthe hydraulic lifter, the stop surface on the inner plunger member andthe opposing stop surface on the compensator member are brought intoengagement to thereby enable forces to be transmitted from the outerplunger member through the compensator member to the inner plungermember. Upon the occurrence of a temporary or momentary slack in thevalve train, a compensator spring presses the compensator memberoutwardly to at least partially reestablish the clearance between thestop surfaces on the inner plunger member and the compensator member tothereby absorb or take up the temporary slack. This taking up of thetemporary slack by the compensator assembly prevents a pumping up" ofthe hydraulic lifter by preventing the check valve assembly associatedwith the inner plunger member from adjusting the position of the innerplunger in response to the occurrence of the temporary slack. Thenegative clearance is taken up by inward movement of the outer plungermember against the influence of the compensator spring I claim 1 Ahydraulic lifter for use in a valve train, said hydraulic liftercomprising a body. first and second plunger members located at leastpartially within said body, a compensator member mounted in said body inassociation with said plunger members, and spring means for biasing saidcompensator member in a first direction away from said, first plungermember to provide a clearance between a stop surface on said firstplunger member and said compensator member and a corresponding lash inthe valve train, said spring means acting between said compensatormember and said first plunger and having a first end portion disposed inengagement with said first plunger member and a second end portiondisposed in engagement with said compensator member, said compensatormember being movable in said first direction under the influence of saidspring means to move said second plunger member away from said firstplunger member and being movable in a second direction into engagementwith the stop surface on said first plunger member upon relativemovement between said plunger members against the bias of said springmeans in response to operation of a cam to thereby take up the valvetrain lash corresponding to the aforesaid clearance.

2. A hydraulic lifter as set forth in claim 1 further including stopmeans associated with said first plunger member for limiting outwardmovement of said compensator member under the influence of said springmeans.

3. A hydraulic lifter as set forth in claim 1 wherein said compensatormember has one surface portion which abuttingly engages a surface ofsaid second plunger member and an opposite surface portion whichabuttingly engages the stop surface on said first plunger member uponthe aforesaid relative movement between said plunger members.

4. A hydraulic lifter for use in a valve train, said hydraulic liftercomprising a body, first and second plunger members located at leastpartially within said body, a compensator member mounted in said body inassociation with said plunger members, spring means for biasing saidcompensator member and said second plunger member away from said firstplunger member to provide a clearance between a stop surface on saidfirst plunger member and said compensator member and a correspondinglash in the valve train, said compensator member being movable intoengagement with the stop surface on said first plunger member uponrelative movement between said plunger members against the bias of saidspring means in response to operation of a cam to thereby take up thevalve train lash corresponding to the aforesaid clearance, stop meansassociated with said first plunger member for limiting outward movementof said compensator member under the influence of said spring means, andsecond spring means for urging said plunger members outwardly of saidbody, said second spring means having a lower spring load than saidspring means for biasing said compensator member and said second plungermember outwardly.

5. A hydraulic lifter for use in a valve train, said hydraulic liftercomprising a body, first and second plunger members located at leastpartially within said body, a compensator member mounted in said body inassociation with said plunger members, said compensator member having atleast a portion thereof disposed between said first and second plungermembers, and spring means for biasing said compensator member and saidsecond plunger member away from said first plunger member to provide aclearance between a stop surface on said first plunger member and saidcompensator member and a corresponding lash in the valve train, saidcompensator member being movable into engagement with the stop surfaceon said first plunger member upon relative movement between said plungermembers against the bias of said spring means in response to operationof a cam to thereby take up the valve train lash corresponding to theaforesaid clearance.

6. A hydraulic lifter for use in a valve train, said hydraulic liftercomprising a body, first and second plunger members located at leastpartially within said body, a compensator member mounted in said body inassociation with said plunger member, spring means for biasing saidcompensator member and said second plunger member away from said firstplunger member to provide a clearance between a stop surface on saidfirst plunger member and said compensator member and a correspondinglash in the valve train, said compensator member being movable intoengagement with the stop surface on said first plunger member uponrelative movement between said plunger members against the bias of saidspring means in response to operation of a cam to thereby take up thevalve train lash corresponding to the aforesaid clearance and having oneannular surface which abuttingly engages an annular surface of saidsecond plunger member and another annular surface which abuttinglyengages the stop surface on said first plunger member upon the aforesaidmovement between said plunger members, and an annular stop means mountedon said first plunger member for engagement with said compensator memberto limit outward movement of said compensator member relative to saidfirst plunger member under the influence of said spring means.

7. A hydraulic lifter as set forth in claim 6 wherein said compensatormember is a washer and said one annular surface is substantially flatand adapted to engage said annular stop means, said spring means beinglocated in said first plunger member in engagement with said otherannular surface.

8. A hydraulic lifter as set forth in claim 6 wherein said compensatormember includes an annular head portion, an annular base portion and acylindrical body portion interconnecting said base and head portions,said annular surfaces being on opposite sides of said head portion, saidbase portion being adapted to engage said annular stop means, saidspring means being located in said first plunger member in engagementwith said base portion.

9. A hydraulic lifter for use in a valve train, said hydraulic liftercomprising a body, first and second plunger members located at leastpartially within said body, a compensator member mounted in said body inassociation with said plunger members, spring means for biasing saidcompensator member and said second plunger member away from said firstplunger member to provide a clearance between a stop surface on saidfirst plunger member and said compensator member and a correspondinglash in the valve train, said compensator member being movable intoengagement with the stop surface on said first plunger member uponrelative movement between said plunger members against the bias of saidspring means in response to operation of a cam to thereby take up thevalve train lash corresponding to the aforesaid clearance and stop meanson said first plunger member for limiting outward movement of saidcompensator member under the influence of said spring means, saidcompensator member being mounted on said first plunger member formovement between a first position and a second position, saidcompensator member in said first position having one surface portion inengagement with said stop means and another surface portion spaced fromsaid stop surface by a distance corresponding to the aforesaidclearance, said compensator member when in said second position havingsaid one surface portion spaced from said stop means by a distancecorresponding to the aforesaid clearance and said other surface portionin engagement with said stop surface.

10. A hydraulic lifter as set forth in claim 9 wherein said stop meansincludes a ring mounted on said first plunger member and said spring.means is mounted in a cavity in said first plunger member and pressessaid compensator member toward said first position.

l]. A hydraulic lifter as set forth in claim 9 wherein said stop surfaceis formed by one portion of the surface means defining an opening insaid first plunger member and said stop means includes another portionof said surface means defining an opening in said first plunger member,said compensator member being at least partially positioned within saidopening and being movable relative to said surface portions.

12. A hydraulic lifter as set forth in claim 11 wherein a second openingis formed in said first plunger member and said spring means is locatedin a cavity formed in said first plunger member between said openings,said compensator member being a pin having opposite end portions locatedin said openings and extending across said cavity.

plunger member and said body member, a passageway disposed in said firstplunger member to provide for fluid flow from said second cavity to saidfirst cavity, valve means associated with said first plunger member andsaid passageway for controlling said fluid flow from said secondcavityto said first cavity, a spring means mounted in said second cavityfor urging said second plunger member outwardly relative to said firstplunger member, stop means mounted on said first plunger member forlimiting outward movement of said second plunger member relative to saidfirst plunger member under the influence of said spring means, a firststop surface formed on said first plunger member, a second stop surfaceformed on said second plunger member, said spring means urging saidsecond stop surface away from said first surface to establish apredetermined clearance therebetween when said second plunger member isin engagement with said stop means, said second plunger member beingmovable relative to said first plunger member against the influence ofsaid spring means in response to the operation of the cam in the valvetrain to bring said first stop surface into engagement with said secondstop surface to thereby take up valve train lash corresponding to theaforesaid clearance.

14. A hydraulic lifter as set forth in claim 13 wherein said stop meansincludes ring mounted in a groove formed on said first plunger member.

15. A hydraulic lifter as set forth in claim 14 wherein said first stopsurface has a generally annular configuration, and

said spring means is located in the cavity in said first plunger memberaxially inwardly of said second plunger member and is circumscribed bysaid first stop surface when said first and second stop surfaces arespaced apart.

16. A hydraulic lifter for use in a valve train, said lifter comprisinga body defining a cavity, first and second plunger members located atleast partially within the cavity in said body,

said first and second plunger members defining a first chamber whichreceives fluid from a source of fluid, said first plunger member andsaid body defining a second chamber which receives fluid from said firstchamber, valve means as sociated with said first plunger member andoperable to provide for fluid flow from said first chamber to saidsecond chamber, and compensating means .for preventing an operation ofsaid valve means in which pumping up of said hydraulic lifter occurs,said compensating means including a compensator member operativelyassociated with said second plunger member and means for moving saidcompensator member so that said compensator member effects movement ofsaid second plunger member away from said first plunger member inresponse to a temporary slack in the valve train.

17. A hydraulic lifter as set forth in claim 16 further including springmeans for biasing said compensator member away from said first plungermember to thereby provide a clearance between a stop surface on saidfirst plunger member and said compensator member.

